Pneumatic Test with U-Tube Vertical Manometer

Be very careful with a U-tube manometer. Many is the time I put pressure or vacuum on one side and nothing on the other side and sent the water in the manometer across the room or worse it was sucked into the vacuum pumps. The U-tube manometer is used to measure a differential pressure. Typically I would start out with atmosphere on both sides and then bring up the pressure or vacuum slowly. I typically used a 50" WC manometer to measure the pressure drop across a flow orifice. So when the valve opens you have 35 mm WC or 25 mm WC vacuum. If one side of the manometer is connected to the valve and the other side is open to atmosphere you should be able to read the pressure vacuum. It might be a good idea to use an adjustable orifice on the atmosphere side to help dampen the inrush of the pressure or vacuum. A bit of a long winded explanation but hopefully it is helpful. Either way good luck

Thank you for your reply,but ı want to know how can we read the U-Tube as pressure/vacuum

ex.for pressure if the 35mmWC is seen above the 0 balance line what is the differantial pressure 35 mmWC or 70 mmWC inculuding below the 0 balance line.

One side will be above zero, the other below, add these two reading = the value of the measured parameter. Example: one side reads -1 the other reads +1 . . . thus the reading = 2 (value of parameter sought)